SMA4F26AY Equivalent & Substitute Parts

Part Overview

The SMA4F26AY is a unidirectional Transient Voltage Suppressor (TVS) diode manufactured by STMicroelectronics, designed for surface mount applications in automotive-grade circuits. This component operates with a 26V reverse standoff voltage and provides transient protection with a 42.1V maximum clamping voltage at peak pulse current of 9.5A. The device is packaged in DO-221AC SMAflat configuration and meets AEC-Q101 automotive qualification standards.

The SMA4F26AY carries a Last Time Buy product status, indicating discontinued production. Equivalent and substitute parts are necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications requiring TVS diode protection in the 26V standoff voltage range.

Substiute Parts

SMA4F26AY

STMicroelectronicsIn Stock: 685SMA4F26AY Datasheet

Current PartRFQ

SM4T30AY

STMicroelectronicsIn Stock: 5845SM4T30AY Datasheet

MFR RecommendedRFQ

SM4T28AY

STMicroelectronicsIn Stock: 15649SM4T28AY Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SMA4F26AY is determined by the following critical electrical and mechanical parameters:

Voltage Parameters: Substitute parts must maintain the same reverse standoff voltage (26V typical) and comparable breakdown voltage (minimum 28.9V) to ensure proper circuit protection thresholds. Clamping voltage and peak pulse current characteristics define the transient suppression capability.

Mechanical Compatibility: Surface mount packaging and automotive-grade qualification (AEC-Q101) are mandatory for direct substitution in existing designs. Package type transitions from SMAflat (DO-221AC) to standard SMA (DO-214AC) represent physical form factor changes that may require PCB layout modifications.

Thermal and Compliance Requirements: Operating temperature range, RoHS compliance status, and moisture sensitivity classification must be evaluated for application-specific requirements. The original part's RoHS non-compliant status contrasts with modern RoHS3-compliant alternatives.

Product Status Consideration: Active product status indicates ongoing availability and manufacturing support, whereas Last Time Buy status indicates limited future supply.

Parameter Comparison

Engineering Selection Recommendations

SM4T30AY (MFR Recommended Substitute): This part is designated as the manufacturer-recommended equivalent and maintains identical reverse standoff voltage (26V) and breakdown voltage (28.9V) specifications. The SM4T30AY offers superior peak pulse current handling (43A versus 9.5A) and is classified as Active product status with ROHS3 compliance. The package transition from SMAflat (DO-221AC) to standard SMA (DO-214AC) requires PCB layout verification. Operating temperature range is reduced to -55°C to 150°C, which is acceptable for most automotive applications. This substitute is appropriate for new designs and ongoing production requiring modern compliance standards.

SM4T28AY (Similar Substitute): This alternative operates at a lower reverse standoff voltage (24V) and breakdown voltage (26.7V), representing a voltage class reduction. The SM4T28AY provides higher peak pulse current capability (46A) and maintains Active product status with ROHS3 compliance. This substitute is suitable only for applications where the lower voltage rating is acceptable and where the 24V standoff voltage provides adequate protection margins. Package form factor is identical to SM4T30AY (DO-214AC, SMA).

Product Status Impact: The SMA4F26AY Last Time Buy status necessitates transition planning. Both substitute parts carry Active status, ensuring long-term supply availability and manufacturing support.

Compliance Considerations: Transition from RoHS non-compliant to ROHS3-compliant alternatives aligns with current regulatory requirements and supply chain expectations for automotive-grade components.

Frequently Asked Questions (FAQ)

Q: Can SM4T30AY directly replace SMA4F26AY without PCB modifications?

A: Electrical substitution is direct; both parts maintain 26V reverse standoff voltage and 28.9V minimum breakdown voltage. However, package form factor differs: SMA4F26AY uses DO-221AC SMAflat leads, while SM4T30AY uses DO-214AC standard SMA leads. PCB footprint verification is required before implementation.

Q: What is the significance of the different peak pulse current ratings?

A: SMA4F26AY specifies 9.5A peak pulse current at 10/1000µs pulse width, while SM4T30AY specifies 43A at 8/20µs pulse width. These represent different test conditions and pulse durations. SM4T30AY demonstrates higher transient suppression capability under the 8/20µs standard test condition commonly used for power line protection applications.

Q: Why does SM4T28AY have a lower voltage rating?

A: SM4T28AY operates at 24V reverse standoff voltage versus 26V for the main part. This represents a different voltage class within the TVS diode product family. Selection of SM4T28AY is appropriate only when circuit protection requirements align with the 24V standoff specification.

Q: Are both substitute parts automotive-qualified?

A: Yes. Both SM4T30AY and SM4T28AY carry Automotive grade classification and AEC-Q101 qualification, meeting automotive industry standards equivalent to the original SMA4F26AY.

Q: What is the impact of RoHS compliance differences?

A: SMA4F26AY is RoHS non-compliant, while both substitutes (SM4T30AY and SM4T28AY) are ROHS3 compliant. For new designs and applications subject to RoHS regulations, the compliant alternatives are required. Existing designs using non-compliant parts may continue with SMA4F26AY stock until exhausted, then transition to compliant alternatives.

Q: How do operating temperature ranges compare?

A: SMA4F26AY operates from -55°C to 175°C (TJ), while both substitutes operate from -55°C to 150°C (TJ). The 25°C reduction in maximum junction temperature for substitutes is acceptable for most automotive applications but should be verified for high-temperature environments.

Q: What packaging considerations apply to substitution?

A: SMA4F26AY uses SMAflat (DO-221AC) packaging with flat leads, while substitutes use standard SMA (DO-214AC) packaging. These represent different physical form factors requiring PCB footprint redesign. Tape & Reel (TR) packaging is consistent across all parts for automated assembly compatibility.